1. Technical Field
The present invention relates to an image forming apparatus that is suited for forming an image on a recording medium particularly with an inkjet recording head.
2. Related Art
Image forming apparatus that form an image on a recording medium such as recording paper with an inkjet recording head are widely known. These image forming apparatus convey the recording medium directly under the recording head and form an image on the recording medium.
In such image forming apparatus, image formation ends up being distorted when the distance between the head plane and the recording medium is uneven. In a worst-case scenario, it is conceivable for the recording head and the recording medium to come into contact with each other such that the recording head sustains damage or the recording medium becomes jammed. For this reason, correcting the shape of the recording medium has, as described in Japanese Patent Application Laid-Open Publication (JP-A) No. 2006-232500, for example, conventionally been performed.
Here, in recent years, image forming apparatus disposed with a switchback conveyance path so that the image forming apparatus can form an image on both sides of the recording medium have been developed. For example, the image forming apparatus described in Japanese Patent Application Laid-Open Publication (JP-A) No. 2006-232500 inverts a recording medium on a switchback conveyance path and conveys the recording medium directly under a recording head.
When an image forming apparatus forms an image on both sides of the recording medium in this manner, immediately after the recording head has formed an image on one surface (front surface) of the recording medium, a rate of moisture absorption of this surface increases in comparison to the opposite surface (back surface), and the one surface (front surface) separates from a surface of to a conveyance path so as to rise from the conveyance path. As a result, when the recording medium is further conveyed under the recording head after the recording medium has been reversed to invert its front and back sides in order to form an image on the back surface thereof; the surface side on which an image was formed and that was separating from the surface of the conveyance path becomes the side that contacts the conveyance path, and the recording medium is conveyed. When the recording medium is held by suction onto a conveyance guide in this state, both leading and trailing edge portions of the recording medium cannot be sufficiently held by suction, and image formation is performed in a state in which both edge portions of the recording medium are separated from the conveyance guide. Consequently, the distance between the head plane and the recording medium becomes uneven, which affects image quality, for example by disrupting image formation. In the worst case, the head and the paper edges may come into contact with each other and lead to ink leakage or head failure.
As a countermeasure, in JP-A No. 2006-232500, there is disclosed forming an image on one surface of recording paper, thereafter controlling deformation of the recording paper before causing the recording paper to switch back, and preventing rising of the leading edge of the recording paper.